Electroretinographic findings in iris neovascularization due to acute central retinal vein occlusion
M. A. Johnson and T. J. McPhee
Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, Md.
Electroretinograms (ERGs) were recorded in 94 patients with central retinal
vein occlusion (CRVO). Of these 94, 11 had neovascularization of the iris
(NVI) at the time of testing, 25 later developed NVI, and 58 did not
develop NVI during a follow-up period that varied from 1 1/2 to 5 years.
The ERG recorded at the patient's presentation visit predicted the
occurrence of NVI in these patients with high sensitivity and specificity.
The most predictive ERG parameters were the semi-saturation constant from
intensity-response analysis (log K), and the implicit times of the scotopic
a- and b-waves and the scotopic 30-Hz flicker response. These parameters
were highly correlated, suggesting that the functional mechanism that
places eyes at risk for NVI in CRVO is unidimensional. Paradoxically, the
most likely candidate for this mechanism is photoreceptor sensitivity loss
due to ischemia.
